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<!----------------------------------------------------------
 
	Copyright (c) 2015-2018 Jean-Marc VIGLINO, 
	released under CeCILL-B (french BSD like) licence: http://www.cecill.info/
	
------------------------------------------------------------>
	<title>ol-ext: Overpass OSM layer</title>
	<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />

	<meta name="description" content="DBPedia layer for OL3" />
	<meta name="keywords" content="ol3, layer, source, vector, wikipedia, dbpedia" />

	<!-- SparQL server only works on http -->
	<script>
		if (location.protocol == 'https:')
		{	location.href = window.location.href.replace(/^https:/,"http:");
		}
	</script>

	<!-- jQuery -->
	<script type="text/javascript" src="https://code.jquery.com/jquery-1.11.0.min.js"></script>

	<!-- Openlayers -->
	<link rel="stylesheet" href="https://openlayers.org/en/latest/css/ol.css" />
	<script type="text/javascript" src="https://openlayers.org/en/latest/build/ol.js"></script>
	<script src="https://cdn.polyfill.io/v2/polyfill.min.js?features=requestAnimationFrame,Element.prototype.classList,URL,Object.assign"></script>
	
	<!-- ol-ext -->
	<link rel="stylesheet" href="../../dist/ol-ext.css" />
	<script type="text/javascript" src="../../dist/ol-ext.js"></script>

	<!-- ol-ext maki and fontawesome defintions used in fontsymbol -->
	<script type="text/javascript" src="../../dist/extra/FontAwesomeDef.js"></script>

	<link rel="stylesheet" href="../style.css" />
	<style>
		#select img
		{	max-height: 300px;
		}
	</style>
</head>
<body >
	<a href="https://github.com/Viglino/ol-ext" class="icss-github-corner"><i></i></a>

	<a href="../../index.html">
		<h1>ol-ext: DBPedia layer</h1>
	</a>
	<p class="info">
		<i>ol.source.Overpass</i> is a vector source that use the 
    <a href="https://wiki.openstreetmap.org/wiki/Overpass_API">Overpass API</a> to load <a href="">OSM</a> features.
    <br/>
    You can use filter to choose what kind of features you want to display on the map.
    <a href="https://wiki.openstreetmap.org/wiki/Overpass_API/Language_Guide#Tag_request_clauses_.28or_.22tag_filters.22.29">See API filter tags documentation.</a>
	</p>

	<!-- DIV pour la carte -->
	<div id="map" style="width:600px; height:400px;"></div>
	<div class="options">
    <ul>
      <li>
        Filter: 
        <select onchange="setFilter(this.value)">
          <option value="highway=bus_stop">highway=bus_stop</option>
          <option value="leisure">leisure</option>
          <option value="leisure,sport=swimming">leisure,sport=swimming</option>
          <option value="highway,highway!~'crossing|signal'">highway</option>
        </select>
      </li>
    </ul>
  </div>
	<div id="select" class="options" >Select an item.</div>
	
<script type="text/javascript">
	// The map
	var map = new ol.Map
		({	target: 'map',
			view: new ol.View
			({	zoom: 15,
				center: [261204.43490751847, 6250258.191535994]
			}),
			interactions: ol.interaction.defaults(),
			layers: [ new ol.layer.Tile({ name:"OSM", source: new ol.source.OSM() })]
		});

  function setFilter(filter) {
    console.log('filter:',filter.split(','))
    vectorSource = new ol.source.Overpass({
      //relation: false,
      filter: filter.split(','), 
      // Tile strategy load at zoom 14
      strategy: ol.loadingstrategy.tile(ol.tilegrid.createXYZ({ minZoom: 14, maxZoom: 14, tileSize:512  })),
      // Bbox strategy : reload at each move
      //strategy: ol.loadingstrategy.bbox,
    });
    vector.setSource(vectorSource);
  }

	// DBPedia layer source
	var vectorSource = new ol.source.Overpass({
    //way: false,
    filter: [ 'highway=bus_stop' ], 
    //filter: [ 'leisure' ], 
    // filter: [ 'leisure', 'sport=swimming' ], 
    // filter: [ 'highway' ], 
    // Tile strategy load at zoom 14
    strategy: ol.loadingstrategy.tile(ol.tilegrid.createXYZ({ minZoom: 14, maxZoom: 14, tileSize:512  })),
		// Bbox strategy : reload at each move
		//strategy: ol.loadingstrategy.bbox,
	});

	// Force layer reload on resolution change 
	map.getView().on('change:resolution', function(evt)
  {	//vectorSource.clear();
    select.getFeatures().clear();
		if (map.getView().getZoom() < 14) $("#select").text("Zoom to load data...");
		else $("#select").first().text("");
	});

	var vector = new ol.layer.Vector({
    name: 'OSM',
		source: vectorSource,
		// Limit resolution to avoid large area request
		maxResolution: 10, // > zoom 14
	});

	map.addLayer(vector);

	// Control Select 
	var select = new ol.interaction.Select({
		hitTolerance: 3,
		condition: ol.events.condition.click
	});
	map.addInteraction(select);
	// On selected
	select.getFeatures().on(['add','remove'], function(e) {
    var info = $("#select").html("");
		if (e.type=="add") {	
      var el = e.element;
			var ul = $('<ul>').appendTo(info);
			var prop = el.getProperties();
			for (var i in prop) {
        if (i!=='geometry') {
          li = $('<li>')
            .html('<i>'+i+"</i>: "+prop[i])
            .appendTo(ul);
        }
			}
		}
	});

</script>

</body>
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